Direct positive emulsion containing a halide releasing compound developed in the presence of an unsubstituted hydrazine

ABSTRACT

Direct positive copies obtained by imagewise exposing a lightsensitive material having a layer of a silver halide emulsion of the type that forms a latent image predominantly within the silver halide grains in which emulsion is incorporated at least one compound setting free iodide ions or at least one compound setting free bromide ions in an aqueous medium together with a fog inhibiting compound and developing thus exposed material with an energetic surface developer in the presence of an unsubstituted hydrazine or a water soluble salt thereof provided by way of the developer solution or by way of a processing liquid applied to the exposed material prior to development. Colored images can be formed as well as black and white images provided color coupling agents and color developing agents are utilized.

United States Patent 1151 3,637,387 Vanreusel et al. 451 Ja 25, 1972 541 DIRECT POSITIVE EMULSION 3,531,290 9/1970 Letzerman ..96/l07 x NTA NIN A HALIDE RELEASING 3,326,689 6/1967 F1x ..96/l06 COMPOUND DEVELOPED IN THE Primary Examiner-Norman G. Torchm PRESENCE OF AN UNSUBSTITUTED Assistant ExaminerRichard E. Fichter HYDRAZINE Attorney-William J. Daniel [72] lnventors: Gerard L. Vanreusel, Hove; Camille A.

Vandeputte, Mortsel, both of Belgium [57] ABSTRACT Direct positive copies obtained by imagewise exposing a light- [73] v Assgnee Gevaert'AGFA Monsel Belgium sensitive material having a layer of a silver halide emulsion of [22] Filed; O t, 24, 1967 the type that forms a latent image predominantly within the silver halide grains in which emulsion is incorporated at least .[21] App! 677765 one compound setting free iodide ions or at least one compound setting free bromide ions in an aqueous medium 52 us. c1 ..96/64, 96/107 member with a fog inhibiting P and developitlg thus 5 exposed material with an energetic surface developer in the 58 Field of Search ..96/64, 107 Pmence of an unsubstituted hydrazine or a Water SO'uble salt thereof provided by way of the developer solution or by way of [561 References Cited a processing liquid applied to the exposed material prior to development. Colored images can be formed as well as black UNITED STATES PATENTS and white images provided color coupling agents and color 3,531,288 9/1970 Jones ..96/108 devebp'ng agents 24 Claims, No Drawings DIRECT POSITIVE EMULSION CONTAINING A HALIDE RELEASING COMPOUND DEVELOPED IN THE PRESENCE OF AN UNSUBSTITUTED HYDRAZINE halide emulsion layer, thus exposed with developing the light-sensitive material an energetic surface processing liquid with which the light-sensitive material is wetted before development In order to stabilize the photographic direct positive image obtained after the developing step the material is generally fixed e.g., in a usual fixing solution such as a thiosulphate solution and washed, whereupon the said material may be dried or glazed.

Thus, the present invention provides a method of producing direct positive images of good quality in a rapid and simple way. This method is particularly suitable for producing continuous tone direct positive images but it is also appropriate for reproducing line originals.

The light-sensitive material of use according to the present invention generally comprises a support, for instance a paper support or a hydrophobic film support that is either transarent or not, to which the light-sensitive silver halide emulsion layer is applied, if need be by means of an appropriate subbing layer. 7

The silver halide emulsion used is of the type in which the latent image is formed mostly or entirely internally in the p-hydroxyphenylglycine 10 g. sodium carbonate (cry st.) I g. water to L000 cc.

and the exposed grains of which are well developable into silver by a developing solution, which acts as a developer for latent image inside the grains, i.e., a so-called intemal" By a silver halide emulsion that mainly forms internal latent image and little external latent image there is more particuminutes at 20 C. in the above internal developer, exhibits a maximum density at least three times and preferably at least test layer of the said silver halide emulsion is equally exposed and then developed for 4 minutes at 20 face" developer. Said preference for a maximum density of at least five times as large particularly appliesto-the case wherein C. in the above surthe method is applied to the to obtain good results.

Silver halide emulsions that meet the above requirement and hence are suitable for being employed in this embodiment The light-sensitive silver according to all known and water-soluble bromide and occasionally iodide, the amounts of which are adapted in view of the final composition aimed at, into a silver chlorobromide or a silver bromide emulsion,

suitable for use according to the present invention reference is made to the specific examples given below.

Into the light-sensitive silver halide material has been incorever composite layer of the light-sensitive material that stands in water-penneable relationship with the light-sensitive silver halide emulsion layer; however, they are preferably present in the light-sensitive silver halide emulsion layer itself. They may be incorporated into the light-sensitive material by soaking the latter before or after the imagewise exposure in an aqueous composition containing them, e.g., the energetic surface developer itself, or by adding them to the coating composition of a particular layer of the light-sensitive material.

The idea of incorporating into the light-sensitive material developer or to a preceding processing liquid for treating the light-sensitive material after the imagewise exposure, is the subject of our British Pat. application No. 47,630/66 entitled: Modified Method of Producing Photographic Images and relating to a slightly different method of producing directpositive images.

As defined above the compounds that set free iodide ions or bromide ions are preferably incorporated into the light-sensitive silver halide emulsion layer itself. They are generally added to the light-sensitive silver halide emulsion after the silver halide has been precipitated and occasionally converted.

For carrying out this embodiment of the invention the compounds that set free iodide ions or bromide ions can be applied in greatly varying concentrations i.e., in concentrations that depend on the nature of the compounds used and of the lightsensitive silver halide emulsion. However, their concentration is in general comprised between 0.01 and 20 g., preferably between 0.1 and 5 g., per mole of silver halide.

The high-maximum density of the direct positive image obtained according to this embodiment of the invention is due to the presence of said compounds setting free iodide or bromide ions. The best results i.e., the highest densities, can be attained when using simultaneously compounds that set free iodide ions and compounds that set free bromide ions, although good results are also attained when using one of both kinds of compounds alone, particularly those setting free iodide ions.

Suitable compounds setting free iodide ions are among others water-soluble iodides, inorganic as well as organic iodides, organic compounds with labile iodine atoms, onium chloroiodates, and molecular iodine and the addition products thereof, e.g., with polyvinyl pyrrolidone, with polyoxyalkylenes and their derivatives, or with quaternary ammonium compounds.

The idea of using molecular iodine and/or its addition products as compounds setting free iodide ions is the subject of our British Pat. application No. 47,629/66 entitled: A Method of Producing Photographic Images" and relating to a slightly different method of producing direct-positive images.

Silver iodide sols are less appropriate for use as compounds setting free iodide ions. Hitherto they proved to be appropriate only when added in high concentrations to the liquid silver halide emulsion just prior to the coating of the latter on a suitable support.

Suitable inorganic iodides are for instance, calcium iodide, ammonium iodide, lithium iodide, magnesium iodide, potassium iodide, sodium iodide, barium iodide, cadmium iodide, and zinc iodide.

Suitable organic iodides are for instance the iodides corresponding to the following structural formula:

H; C N+ C H;

tetramethylammonium iodide,

(H; C H2) |N+]I '3I2 tetraeth ylammonlum iodide-3-diiodine,

i H3 C(CH2) 1 I'\lNH:

O H; 1, l, l-dodeeyldtmethylhydrazinium (1+) iodide,

O H 0 Ha l-msthyl-8-hydr0xy-quinoliuium iodide,

t,2,3,4-tetrahydro-8-hydroxy-l,ldimothyl-qulnollulum ltldld.

benzyltriphenylphosphonlmn iodide diphenyl-iodonlum iodide.

Organic compounds with labile iodine atom, which have proved to be suitable for use according to the invention, are for instance mono-iodo-acetic acid and 4-iodo-butane sulfonic acid potassium salt.

trimethyl-(o-methox ycarbon yl)-anilinium dichlol'oiodat e.

benzyltripheiiyl-pliosplmntum rlichloroiodato Suitable compounds setting free bromide ions are among others inorganic and organic bromides such as ammonium bromide, lithium bromide, sodium bromide, potassium bromide, magnesium bromide, calcium bromide, barium bromidc, cadmium bromide and zinc bromide as inorganic bromides and tclraethyl ammonium bromide and ethyl pyridinium bromide as organic bromides. Organic compounds with labile bromine atom such as monobromo-acetic acid are also suitable for being used in the present process as compounds setting free bromide ions.

In a first step for the preparation of the direct positive image the light-sensitive material is "imagewise exposed to the original to be reproduced. This exposure can either be a highintensity exposure such as a flash exposure or a normal intensity exposure such as a daylight exposure, as well as a low-intensity exposure such as an exposure by means ofa printer or an exposure of still lower intensity, the exposure time being dependent on the sensitivity of the light-sensitive material for the direct positive image formation, which sensitivity according to the present invention may be a camera speed as well as a lower sensitivity.

In a further step of the direct positive image formation according to this embodiment of the present invention the imagewise exposed light-sensitive material is soaked with an energetic surface developer for instance by conducting the material through a tray containing such developer.

The developer of use in this embodiment of the invention must be a surface" developer i.e., a developer that contains no or at least no effective amount of solvents for silver halide. In this case by solvents for silver halide there are meant particularly strong solvents for silver halide such as water-soluble thiocyanates, thiosulfates, ammonia, etc. Indeed, compounds that may be considered to be but very weak solvents for silver halide, such as sodium sulfite in the case the silver halide is silver bromide, silver chlorobromide, or silver bromoiodide, may be present in the developer.

The choice of the developing substances also determines the energy of the developer. Examples of suitable developing substances are among others the combination of l-phenyl-3- pyrazolidinone with hydroquinone and the combination of monomethyl-p-aminophenol sulfate with hydroquinone. In general there may be said that the more energetic the developer, the better the result obtained.

For carrying out the process according to the invention the developing agents may also be incorporated partially or even completely into the light-sensitive material. This incorporation may be accomplished during the preparation stage of the material or later on by means of a processing liquid, with which the light-sensitive material is wetted prior to the development of the direct positive image. In doing so the energetic surface" developer can be reduced to a mere alkaline liquid substantially free from developing agents. Such an alkaline aqueous liquid, often called activator" offers the advantage of having a longer activity i.e., of being less rapidly exhausted.

The developer (occasionally activator") and/or another processing liquid can be supplied in an amount, which suffices for the treatment of exactly one foil of light-sensitive material. In this case this liquid is called a single-use bath. A bath of this type offers the advantage that ageing and contamination of-tl ie bath composition are eliminated.

Hydrazine and/or at least one water-soluble salt of hydrazine have to be added to the energetic surface developer and/or to a preceding processing liquid for the light-sensitive material. These compounds cause the formation of a latent direct positive image that will be developable by the energetic surface developer. The best results are obtained with hydrazine and/or at least one water-soluble salt of hydrazine added to the developer itself. When using in the method of the invention another processing liquid incorporating hydrazine and/or a salt thereof this liquid is preferably employed just before the development step and after the exposure step anyway. The pH of the liquid, to which the hydrazine and/or salts thereof have been added is preferably fairly high and in most cases amounts to at least about 10. In addition thereto a preliminary separate processing liquid containing hydrazine and/or salts thereof, may comprise other ingredients that otherwise would have been incorporated into the developer. Wetting of the light-sensitive material by means of the liquid composition to which have been added hydrazine and/or at least one water-soluble salt thereof can occur in any way, such as by soaking or by wetting only one side of the light-sensitive material, e.g., by means of a lick roller, by spreading a paste e.g., contained in a pod, or by spraying.

For the present application hydrazine and its salts are usually added in a concentration comprised between i and 50 g., preferably between 5 and 20 g. per liter of processing liquid irrespective of whether this liquid is the developer liquid itself or another processing liquid with which the light-sensitive material is wetted prior to the development. Examples of water-soluble salts of hydrazine are hydrazine hydrochloride, hydrazine oxalate and hydrazine phosphate.

According to the method of the invention the fog caused normally by the hydrazine and/or its water-soluble salts alone, can also be produced partly by an overall exposure of the light-sensitive material to actinic light of low intensity during development. Especially for the preparation of color images preference is mostly given to a combined use of the hydrazine and/or the water-soluble salts thereof with such an overall exposure. More particulars about the execution of such an overall exposure can be found in the published Dutch Pat. applications 6,605,891 and 6,605,890.

For one skilled in the art it was not obvious at all to try to replace at least partially the overall exposure step during development in the process according to the US. Pat. applications No. 546,528 and 546,640which step is very specific since it cannot be carried out before or after the development, by the use of very specific fogging agents in at least one of the processing liquids.

As already stated above, the direct positive images obtained according to this embodiment of the present invention show very high-maximum densities and have sufficiently lowminimum densities.

This minimum density can be lowered yet by incorporating a fog-inhibiting compound into the light-sensitive material of use for carrying out this embodiment of the present invention. This fog'inhibiting compound must be present in effective contact with the silver halide emulsion layer. By in effective contact" is meant that the fog-inhibiting compound is provided in the light-sensitive material on a place from which it can act upon the silver halide emulsion layer at the appropriate moment, in this case during the soaking at the lightsensitive material with the developer. The fog-inhibiting compound is preferably incorporated into the silver halide emulsion layer itself, but may also be present in another waterpermeable nonlight-sensitive layer of the light-sensitive material such as a covering layer or an intermediate layer, from which it is dissolved by the developer liquid and diffuses to the light-sensitive layer. It is even possible to incorporate considerable amounts of the fog-inhibiting compound into the developer liquid.

The fog-inhibiting compounds give rise to a lowering of the minimum density of the direct positive image even when present only in small amounts. They are very efficient when applied in the common fog-inhibiting amounts. The best results i.e., the most clear minimum densities are however attained when using the fog-inhibiting compounds in amounts larger than the common fog-inhibiting amounts i.e., in amounts that normally are not applied to light-sensitive materials since with such amounts the light-sensitive material would be too strongly desensitized. What is surprising now is that these large amounts of fog-inhibiting compound do not lower the direct positive image sensitivity of the light-sensitive material but in most cases even enhance it and also do not prevent the formation of a direct positive image with good maximum density. Specific data about the concentrations in which the fog-inhibiting compounds are generally employed and give the best results for the process according to the present invention can hardly be given since these concentrations are widely divergent according to the nature of the foginhibiting compound and the kind of silver halide emulsion layer used. For instance in the case of a silver bromide emulsion layer considerably less fog-inhibiting compound must be used than in the case of a silver chlorobromide emulsion layer for attaining almost equivalent results.

Fog-inhibiting compounds of the following classes have proved to be particularly suitable for being applied in this embodiment of the invention: the class of the heterocyclic thione compounds such as 4-phenyl-M- l ,2,4-triazoline--thione, 3-phenylA -l ,2,4-triazoline-5 -thione, l-methyl-2-tetrazoline-Sthione, l-phenyl-2-tetrazoline-5-thione,

l-( l-naphthyl)-2-tetrazoline-5-thione, 1-(Z-naphthyl)-2-tetrazoline-5-thione,

l-( 9-anthyrl )-2-tetrazoline-5-thione,

l-( 3 ,4,-dichlorophenyl )-2-tetrazoline-5-thione,

l-( o-methoxy-phenyl)-2-tetrazoline-5-thione,

i-(o-biphenyl )-2-tetrazoline-5-thione, l-(p-biphenyl)-Z-tetrazoline-S-thione,

1-( 2-naphthyl )-4,4,6-trimethyl-l ,2,3 ,4-tetrahydropyrimidine- 2-thione,

the class of the aromatic and aliphatic mercapto compounds such as:

2-mercapto-ethyl carbanilate;

the class of the benzotriazoles such as:

5-( 3-phenylureido)- l H-benzotriazole; and

the class of the fused OXO-COUlpOUl'ldS containing at least two nitrogen atoms such as:

S-nonyl-7-oxo-4,7-dihydro-s-triazole[ l,5-a]-pyrimidine,

and

2-methyl-4-hydroxypyrimido-[ l ,2-al-benzimidazole.

It will be understood that these classes are intended to refer also to the tautomeric structures of said compounds and to salts of said compounds or occasionally of said tautomeric structures. Mixtures of two or more fog-inhibiting compounds may also be employed.

in carrying out this embodiment of the invention the maximum or minimum density of the direct positive image can still be improved and the characteristics of the light-sensitive material can be altered by using all kinds of ingredients which are generally known in the art of emulsion preparation and some of which will be set out specifically hereinafter.

Most of these ingredients are preferably incorporated into the light-sensitive material itself, in effective contact with the silver halide emulsion layer and favorably in the latter layer itself. Many of these ingredients, however, may be incorporated into the energetic surface developer with the same favorable result. Combinations of two or more of said ingredients, of course, may also be used.

Among the said ingredients may be mentioned some binders for at least partially replacing gelatin as a binder for the silver halide grains and referred to already above in the description, further optical sensitizers and moistening agents such as polyalkylene glycols, i.a. polyethylene glycols, sulfonated fatty acids, saponine and the like. The presence of optical sensitizers and of polyalkylene glycols in the silver halide emulsion layer-in most cases has a favorableeffect o n themaximum density of the direct positive image. Still further ingredients are mentioned later on in the description.

This embodiment for producing direct positive images is not restricted to black-and-white photography; it may also be applied for the preparation of direct positive color images by carrying out the development in an energetic color developer in the presence of a color coupler and by bleaching away the silver developed. The lightsensitive material, of course, may be a multilayer color material each layer of which absorbs a particular part of the spectrum and for which layers appropriate color couplers are provided. In addition to their developing or coupling action many color developing compounds and color couplers exert an advantageous effect on the mechanism of the direct positive image production itself in that they contribute to a higher maximum and/or a lower minimum density.

The following are examples illustrating the process of the present invention.

EXAMPLE 1 A gelatino silver bromide emulsion that mainly formed internal latent image and little external latent image was prepared through conversion of a silver chloride emulsion by very slowly adding to said emulsion while stirring a 35 percent aqueous potassium bromide solution in an amount that was 70 percent higher than the amount theoretically necessary for converting all the silver chloride. The emulsion was then kept for 1 hour at 60 C. After the emulsion had been chilled and allowed to gel for 6 hours the emulsion was noodled. The noodles were washed for 1 hour with water 10 liters of water per minute). By heating the washed noodles a liquid silver bromide emulsion containing 50 g. of gelatin and 0.4 mole of silver bromide per kg. was formed.

To this liquid emulsion potassium iodide was added as follows: to a first part of the emulsion 6 ccs. of a 5 percent aqueous potassium iodide solution were added per kg., to a second part 10 ccs. of such solution were added per kg. and to a third part 20 ccs. ofsuch solution were added per kg.

Each of the light-sensitive emulsions obtained was coated, practically immediately after the addition of the potassium iodide solution, on a baryta-coated paper support of g./sq.m. in such a way that an amount of silver halide equivalent to 4 g. of silver nitrate was present per sq.m. of light-sensitive material.

The emulsion layer of each of the materials was covered with a conventional hardened gelatin antistress layer.

The three silver halide materials obtained were further treated in a completely identical way. Each material was imagewise exposed for l/ 1 0,000 see. through a step-wedge by means of a flash exposure of 130 lux sec. Then each material was developed for 4 min. at 20 C. in a surface" developer of the following composition:

hydroquinone l5 g. l-phenyl-3-pyrazolidinone l g. anhydrous sodium carbonate 30 g. anhydrous sodium sulfile 40 g. hydrazinium oxalate 9 g. water up to 1,000 cc.

The pH was adjusted to l 1.

Each of the light-sensitive materials was then fixed, rinsed and dried in the conventional way.

A direct positive image of the original was formed in each of the three materialsv The three images all had a low-minimum density and a high-maximum density, which was the higher, the more potassium iodide had been incorporated into the light-sensitive material. As compared with a direct positive image produced in the same manner but with a light-sensitive material containing no potassium iodide, the direct positive images produced according to the method of the invention as described in this example, showed a much higher maximum density and practically the same minimum density.

EXAMPLE 2 Example 1 was repeated but hydrazinium oxalate was omitted from the developer, and after the imagewise exposure and right before the development for 4 minutes each of the light-sensitive materials was dipped into the following solution at C., the pH of which had been adjusted to l l:

potassium carbonate g. hydrazinium oxalate 9 g. water to make L000 cc.

A somewhat lower maximum density was reached than in the corresponding images of example 1.

EXAMPLE 3 15 Example 1 was repeated as far as the light-sensitive material, in which the highest amount of potassium iodide had been incorporated, was concerned. However, immediately after having incorporated said potassium iodide and before coating, 5 ccs. of a 5 percent solution in ethanol of l-(omethoxylphem yl)-2-tetrazoline-5-thione were also added to the silver halide emulsion.

The direct positive image produced had a minimum density lower than that produced in the corresponding material of example where no fog-inhibiting agent had been incorporated into the light-sensitive material. lts maximum density was almost unaltered in comparison with the material comprising no fog-inhibiting agent.

3O EXAMPLE 4 Example 3 was repeated, with the proviso, however, that the following surface" developer (activator comprising a fog-inhibiting agent) was used:

anhydrous sodium carbonate 30 g. anhydrous sodium sull'ile 40 g. hydrazine 9 g. water up to 1,000 cc.

The pH was adjusted to ll.

The silver halide emulsion layer contained also 1 g. of hydroquinone, 250 mg. of l-phenyl-3-pyrazolidinone, l g. of formaldehyde-bisulfite, and 0.1 g. of potassium metabisulfite per sq.m.

A direct positive image of good quality was formed.

We claim:

l. A method of producing a photographic direct positive image comprising the steps of:

imagewise exposing a light-sensitive material, which comprises a layer of a silver halide emulsion of the type that forms a latent image predominantly within the silver halide grains, said silver halide emulsion being one which upon exposure to a light intensity scale for a fixed time between one-hundredth and 1 second and development for 3 minutes at 20 C. in an internal developer consisting hydroquinonc 15 g. monomethyl-p-uminophenol sulfate 15 g. sodium sulfite (anhydrous) 50 g. potassium bromide l0 g. sodium hydroxide 25 g sodium thiosulfate (cryst.) 20 g. water to 1,000 cc 20 C. in a surface developer, consisting of p-hydroxyphenyl glycine 10 g. sodium carbonate lcryst.) I00 g. water to L000 cc.

said emulsion layer having incorporated therein subsequent to precipitation of the silver halide of said emulsion at least one halogen ion-releasing compound other than silver halide of the group consisting of compounds which set free iodide ions in an aqueous medium and compounds which set free bromide ions in an aqueous medium, said emulsion layer also having incorporated therein a fog-inhibiting compound in an amount larger than normal fog-inhibiting amounts, and developing the thus exposed light-sensitive material with an aqueous energetic surface developer in the presence of unsubstituted hydrazine or a water-soluble salt thereof said unsubstituted hydrazine or water-soluble salt thereof being supplied from an aqueous solution.

2. The method of claim 1 wherein said unsubstituted hydrazine or water soluble salt thereof is present in said aqueous developer solution.

3. The method of claim 1 wherein said unsubstituted hydrazine or water-soluble salt thereof is present in an aqueous processing liquid with which said light-sensitive material is wetted prior to said development.

4. The method of claim 14 wherein said unsubstituted hydrazine or water-soluble salt thereof is present in an aq ueous processing liquid with which said light-sensitive material is wetted prior to said development, said liquid having a pH of at least about 10.

5. A method according to claim 1, wherein the fog-inhibiting compound is a fog-inhibiting compound of the class of the heterocyclic thione compounds, of the class of the aromatic or aliphatic mercapto compounds, of the class of the benzotriazoles, or of the class of the fused oxo compounds containing at least two nitrogen atoms.

6. A method according to claim 1, wherein the fog-inhibiting compound is l(o-methoxy-phenyl)-2-tetrazoline-5-thione.

7. A method according to claim 1 wherein the silver halide emulsion is at most slightly chemically ripened.

8. A method according to claim 1, wherein the silver halide emulsion is a silver chlorobromide emulsion comprising at least 20 mole percent of silver bromide or a silver bromide emulsion, which emulsions may contain at most 5 mole percent of silver iodide relative to the total amount of silver halide.

9. A method according to claim 8, wherein the silver halide emulsion is prepared by the so-called conversion method.

10. A method according to claim 1, wherein a polyalkylene glycol is present in the light-sensitive material in effective contact with the silver halide emulsion layer.

11. A method according to claim 1, wherein the silver halide emulsion comprises polyvinyl pyrrolidone.

12. A method according to claim 1, wherein the silver halide emulsion comprises a latex.

13. A method according to claim 1, wherein the pH of the processing liquid, whereto said hydrazine or water-soluble salt, thereof has been added, is at least about 10.

14. A method according to claim 1, wherein the light-sensitive material is developed with an energetic color developer in the presence of a color coupler and the silver developed is bleached away.

15. A method according to claim 14, wherein several silver halide emulsion layers constitute a multilayer color material each layer of which absorbs a particular part of the spectrum and for each of which layers an appropriate color coupler is provided.

16. A method according to claim 14, wherein the fog-inhibiting compound is a fog-inhibiting compound of the class of the heterocyclic thione compounds, of the class of the aromatic or aliphatic mercapto compounds, of the class of the benzotriazoles, or of the class of the fused oxo compounds containing at least two nitrogen atoms.

17. A method according to claim 14, wherein the fog-inhibiting compound is 1(o-methoxy-phenyl)-2-tetrazoline-5- thione.

18. A method according to claim 14, wherein the silver halide emulsion is at most slightly chemically ripened.

19. A method according to claim 14, wherein the silver halide emulsion is a silver chlorobromide emulsion comprising at least 20 mole percent of silver bromide or a silver bromide emulsion, which emulsions may contain at most mole percent of silver iodide relative to the total amount of silver halide.

20. A method according to claim 19, wherein the silver halide emulsion is prepared by the so-called conversion method.

21. A method according to claim 14, wherein the light-sensitive material is overall exposed during the development to actinic light of low intensity.

22. A method according to claim 14, wherein at least part of the developing substance is present in the light-sensitive material in effective contact with the silver halide emulsion layer.

23. A method according to claim 1, wherein at least part of the developing substance is present in the light-sensitive material in efiective contact with the silver halide emulsion layer.

24. The method of claim 14 wherein said unsubstituted hydrazine or water-soluble salt thereof is present in said aqueous developer solution. 

2. The method of claim 1 wherein said unsubstituted hydrazine or water soluble salt thereof is present in said aqueous developer solution.
 3. The method of claim 1 wherein said unsubstituted hydrazine or water-soluble salt thereof is present in an aqueous processing liquid with which said light-sensitive material is wetted prior to said development.
 4. The method of claim 14 wherein said unsubstituted hydrazine or water-soluble salt thereof is present in an aqueous processing liquid with which said light-sensitive material is wetted prior to said development, said liquid having a pH of at least about
 10. 5. A method according to claim 1, wherein the fog-inhibiting compound is a fog-inhibiting compound of the class of the heterocyclic thione compounds, of the class of the aromatic or aliphatic mercapto compounds, of the class of the benzotriazoles, or of the class of the fused oxo compounds containing at least two nitrogen atoms.
 6. A method according to claim 1, wherein the fog-inhibiting compound is 1(o-methoxy-phenyl)-2-tetrazoline-5-thione.
 7. A method according to claim 1 wherein the silver halide emulsion is at most slightly chemically ripened.
 8. A method according to claim 1, wherein the silver halide emulsion is a silver chlorobromide emulsion comprising at least 20 mole percent of silver bromide or a silver bromide emulsion, which emulsions may contain at most 5 mole percent of silver iodide relative to the total amount of silver halide.
 9. A method according to claim 8, wherein the silver halide emulsion is prepared by the so-called conversion method.
 10. A method according to claim 1, wherein a polyalkylene glycol is present in the light-sensitive material in effective contact with the silver halide emulsion layer.
 11. A method according to claim 1, wherein the silver halide emulsion comprises polyvinyl pyrrolidone.
 12. A method according to claim 1, wherein the silver halide emulsion comprises a latex.
 13. A method according to claim 1, wherein the pH of the processing liquid, whereto said hydrazine or water-soluble salt, thereof has been added, is at least about
 10. 14. A method according to claim 1, wherein the light sensitive material is developed with an energetic color developer in the presence of a color coupler and the silver developed is bleAched away.
 15. A method according to claim 14, wherein several silver halide emulsion layers constitute a multilayer color material each layer of which absorbs a particular part of the spectrum and for each of which layers an appropriate color coupler is provided.
 16. A method according to claim 14, wherein the fog-inhibiting compound is a fog-inhibiting compound of the class of the heterocyclic thione compounds, of the class of the aromatic or aliphatic mercapto compounds, of the class of the benzotriazoles, or of the class of the fused oxo compounds containing at least two nitrogen atoms.
 17. A method according to claim 14, wherein the fog-inhibiting compound is 1(o-methoxy-phenyl)-2-tetrazoline-5-thione.
 18. A method according to claim 14, wherein the silver halide emulsion is at most slightly chemically ripened.
 19. A method according to claim 14, wherein the silver halide emulsion is a silver chlorobromide emulsion comprising at least 20 mole percent of silver bromide or a silver bromide emulsion, which emulsions may contain at most 5 mole percent of silver iodide relative to the total amount of silver halide.
 20. A method according to claim 19, wherein the silver halide emulsion is prepared by the so-called conversion method.
 21. A method according to claim 14, wherein the light-sensitive material is overall exposed during the development to actinic light of low intensity.
 22. A method according to claim 14, wherein at least part of the developing substance is present in the light-sensitive material in effective contact with the silver halide emulsion layer.
 23. A method according to claim 1, wherein at least part of the developing substance is present in the light-sensitive material in effective contact with the silver halide emulsion layer.
 24. The method of claim 14 wherein said unsubstituted hydrazine or water-soluble salt thereof is present in said aqueous developer solution. 